Not much.
As a resident of Choctaw County, Gaines enlisted with Capt Murphy's Curry Dragoons from Dallas and Perry County, Nov 18, 1861. This company served independently until assigned to a battalion of four Alabama companies led by Capt. Thomas F Jenkins. Murphy's company joined after the Battle of Shiloh, but before the battalion became part of the 3rd Alabama Cavalry.

Evidently Gaines left Confederate service about this time (summer 1862). On July 1, 1862, the Curry Dragoons became Company F, 3rd Alabama Cavalry. Subsequent records show that he secured a substitute and went home. On Dec 5, 1863, Gaines was elected 2nd Lieut of Capt Tutt's Cavalry Company from Choctaw County. The record shows Gaines as a resident of Mount Sterling. He was paroled with Co F, Hatch's 8th Alabama Cavalry, May 12, 1865.

Bottom line -- Gaines may have served a few days with the 3rd Alabama Cavalry, but probably not at all. Gaines served as an officer of Co F, Hatch's 8th Alabama Cavalry, for over a year (April 1864 when the regiment organizaed to May 1865).

Do you have family from the SW corner of Alabama?